According to a statement issued by the company, Thummalapally's appointment became effective from April 20.
"I am delighted that Ambassador Thummalapally has agreed to join our Board of Directors. He had a very successful track record in the corporate world and provided distinguished service to the US Government.
"I am confident that he will bring significant new perspectives and guidance to our Board and leadership team," BVR Mohan Reddy, founder and chairman, Cyient said.
Commenting on his appointment, Thummalapally said, "I have been impressed with Cyient's growth, diversification and global track record in the engineering and technology services industry.
As US Ambassador to Belize from 2009 to 2013, Thummalapally helped strengthen bilateral ties between the two countries in the areas of economic development, education, citizen security and healthcare.
Thumallapally also served in various capacities in the USA government.
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